--- title: Relaying outbound mail: DKIM, client IPs, and visibility description: Running your own mail server while relaying outbound through a sending provider introduces three key challenges. First, DKIM signing: your server and the... canonical: https://daily.dev/posts/relaying-outbound-mail-dkim-client-ips-and-visibility-lm5r3yjpy twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Relaying outbound mail: DKIM, client IPs, and visibility | daily.dev og:description: Running your own mail server while relaying outbound through a sending provider introduces three key challenges. First, DKIM signing: your server and the... og:url: https://daily.dev/posts/relaying-outbound-mail-dkim-client-ips-and-visibility-lm5r3yjpy og:image: https://api.daily.dev/og/posts/LM5R3YJpY.png og:image:alt: Relaying outbound mail: DKIM, client IPs, and visibility og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Relaying outbound mail: DKIM, client IPs, and visibility **[/dev/io](https://daily.dev/sources/iodev)** · 7 min read · 0 upvotes · 0 comments ## Summary Running your own mail server while relaying outbound through a sending provider introduces three key challenges. First, DKIM signing: your server and the provider both sign messages, but you must exclude headers the relay rewrites (like Message-ID) from your own signature to avoid verification failures. Second, SPF is evaluated against the envelope sender (MAIL FROM), not the From header — providers use their own bounce subdomain, so your apex SPF record only matters for direct sends bypassing the relay. Third, visibility gaps: your logs only confirm the relay accepted the message; actual delivery outcomes (bounces, deferrals, spam filing) are only visible through DMARC aggregate reports, TLS-RPT, or provider webhook/API events. Additionally, using PROXY protocol preserves real client IP addresses through NAT/proxy hops, preventing shared abuse-control fate across all clients. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [SPF, DKIM, and DMARC explained for developers](https://daily.dev/posts/spf-dkim-and-dmarc-explained-for-developers-mbs1noovg) · Flavio Copes · 2 upvotes · 1 comments - [DMARC reports are the only outside view of your mail](https://daily.dev/posts/dmarc-reports-are-the-only-outside-view-of-your-mail-bzxwpayb1) · /dev/io · 0 upvotes · 0 comments - [Email is crazy](https://daily.dev/posts/email-is-crazy-y6xb4vf9s) · Lobsters · 0 upvotes · 0 comments - [SPF Alignment: Why is it Important for Improving DMARC](https://daily.dev/posts/spf-alignment-why-is-it-important-for-improving-dmarc-voyvelyv6) · Security Boulevard · 0 upvotes · 0 comments --- Tags: [#security](https://daily.dev/tags/security) [View this post on daily.dev](https://daily.dev/posts/relaying-outbound-mail-dkim-client-ips-and-visibility-lm5r3yjpy) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Relaying outbound mail: DKIM, client IPs, and visibility","url":"https://daily.dev/posts/relaying-outbound-mail-dkim-client-ips-and-visibility-lm5r3yjpy","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/relaying-outbound-mail-dkim-client-ips-and-visibility-lm5r3yjpy"},"datePublished":"2026-07-26T13:25:24.428Z","dateModified":"2026-07-26T13:25:47.633Z","description":"Running your own mail server while relaying outbound through a sending provider introduces three key challenges. 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